A member of Lewis and Clark's exploratory team hiding up a tree after having shot a bear. Originally published in 'Journal of Voyages' (1811) by Peter Gass. Photo by Hulton Archive / Getty Images

Before Lewis and Clark set out to explore the western side of the continent, they tried to prepare for every possible contingency — including medical conditions like constipation. Join the guys as they explore how a dangerous laxative didn’t just save members of the expedition, but also may have preserved their campsites for posterity.